The present invention relates to low energy slip rings, and more particularly, to gold based contact materials fabricated by internal oxidation for use as slip ring material.
Materials suitable for use in low energy slip rings should have high wear resistance, low contact resistance, and a homogeneous and uncontaminated microstructure. Accordingly, such materials must have high conductivity, high hardness and wear resistance, high tarnish resistance, low contact noise, and little or no tendency towards catalytic formation of friction polymers. In the past, these considerations have led to a virtually exclusive dependence upon gold based materials. Currently used gold based materials utilize cold working, solid solution hardening, precipitation hardening, or order hardening which generally benefits strength, hardness and wear resistance but have detrimental effects on the electrical and chemical properites of gold.
Nickel, cobalt, or cadmimum hardened electroplated gold exhibit high hardness, high wear resistance and have a reasonably high conductivity, but such materials often have included contaminates such as KCN, porosity, codeposited polymers, and the like. Moreover, it is hypothesized that such materials have a nonhomogeneous structure. Additionally, the properties of hardened electroplated gold are strongly dependent upon the substrate and plating conditions. Thus, consistantly high quality electroplates require not easily achieved stringent controls during processing. Accordingly, it is desirable to provide a gold-based material which will exhibit high wear resistance, high hardness, high strength, and high conductivity with a homogeneous and uncontaminated structure.